EPON system and method for traffic scheduling in EPON system

In an Ethernet passive optical network (EPON) system and a method for traffic scheduling in the EPON system, the method comprises: dividing a periodic transmission cycle between an optical line termination (OLT) and an optical network unit (ONU) for upstream traffic time band assignment into an Expedited Forwarding (EF) sub-cycle preset for EF traffic and an Assured Forwarding (AF) sub-cycle dynamically set for AF and BE traffic; dynamically assigning, by means of the OLT receiving ONU queue length information from the ONU, a first AF sub-cycle band using the queue length information and the preset EF sub-cycle band; and granting to the ONU, by means of the OLT, a first preset EF sub-cycle band, the dynamically assigned first AF sub-cycle band, and a second preset EF sub-cycle band. Thus, EF traffic band assignment for the next cycle is performed one cycle in advance, thereby reducing idle time and significantly enhancing overall bandwidth efficiency.